U.S. marathon runner trains at high altitude for London Olympics

U.S. marathon runner Meb Keflezighi trains for the London 2012 Olympics in Mammoth Lakes, Calif. on Wednesday, May 30.

Lucy Nicholson / Reuters

U.S. marathon runner Meb Keflezighi trains for the London 2012 Olympics.

Lucy Nicholson / Reuters

U.S. marathon runner Meb Keflezighi.

Olympic silver medalist Meb Keflezighi, 37, is the oldest American ever to qualify for the Olympic marathon. He trains at an altitude of around 9,000 feet in Mammoth to increase his red blood cells and boost his endurance.